Author Topic: Failure-advice needed (Success now)  (Read 9608 times)

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Offline Badger

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Re: Failure-advice needed
« Reply #15 on: January 22, 2018, 04:28:01 pm »
      DC, different things work for different people but this is one of the reasons I started going to full draw weight almost right from the beginning. I don't floor tiller near as much as I used to. If I am making a 50# bow I want the weakest part of that limb to be about 70# when I start. Then I know I can go to my full 50# on every pull even if it only moves a few inches. When you are tillering from a lighter weight than full draw weight there is always that risk of surprises as you increase the draw weight. Especially on high stress designs like this one. You really did do an otherwise real nice job on the bow.

Offline DC

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Re: Failure-advice needed
« Reply #16 on: January 22, 2018, 06:35:12 pm »
I do much the same. If it was the 30# I mentioned that's just what it dropped to when everything went west. When I tiller I pull to 40# because that's the weight I want.

Offline DC

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Re: Failure-advice needed
« Reply #17 on: January 22, 2018, 06:48:02 pm »
Seems to me the real lesson here is that plain old yew just can't quite compete with ocean spray  ;)
Sometimes I wonder. :D

Offline Badger

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Re: Failure-advice needed
« Reply #18 on: January 22, 2018, 06:51:08 pm »
      Designs like that can be challenging I know that sinking feeling you are talking about when you sort of feel like the weight is dropping while you are holding it.

Offline bradsmith2010

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Re: Failure-advice needed
« Reply #19 on: January 22, 2018, 07:04:08 pm »
i think when you made the bow wider it changed alot of things and as the weight got lower,, made the boo to thick relative to the belly,, (-P

Offline Badger

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Re: Failure-advice needed
« Reply #20 on: January 22, 2018, 07:17:51 pm »
i think when you made the bow wider it changed alot of things and as the weight got lower,, made the boo to thick relative to the belly,, (-P

   You are probably right on Brad I didn't even think about the bamboos thickness.

Offline DC

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Re: Failure-advice needed
« Reply #21 on: January 22, 2018, 07:25:00 pm »
I considered that but then I considered a lot of things. ::) I'm rebuilding it and I'm making the hooks shorter and sharper, about a 2" radius. That will reduce the amount of twisting that I will have to worry about so I can make it a little narrower. Also the only scrap Yew I had for new belly lams is a little narrower so one way or tother it's going to be narrower. Maybe 1 1/8" instead of 1 1/4".

Offline DC

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Re: Failure-advice needed
« Reply #22 on: January 22, 2018, 07:31:07 pm »
 One of the things I can't change on the rebuild is the boo thickness, at least not the way I'm doing it. So hopefully making it a little narrower and with a couple more inches of working limb due to the smaller hooks I'll be OK. We'll see. I hope I made the lams thick enough.

Offline bradsmith2010

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Re: Failure-advice needed
« Reply #23 on: January 22, 2018, 07:51:46 pm »
your next one will be great I am sure,, (SH)

Offline Badger

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Re: Failure-advice needed
« Reply #24 on: January 22, 2018, 08:08:11 pm »
I considered that but then I considered a lot of things. ::) I'm rebuilding it and I'm making the hooks shorter and sharper, about a 2" radius. That will reduce the amount of twisting that I will have to worry about so I can make it a little narrower. Also the only scrap Yew I had for new belly lams is a little narrower so one way or tother it's going to be narrower. Maybe 1 1/8" instead of 1 1/4".

  It might take you a few bows to nail it down

Offline vinemaplebows

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Re: Failure-advice needed
« Reply #25 on: January 22, 2018, 10:39:23 pm »
This one is two piece spliced and I went to great pains to copy the amount of deflex that Marc used. For some reason it doesn't show in the picture. This pic shows it better.

Your not kidding, can't tell it from the first pics...:)
Debating is an intellectual exchange of differing views...with no winners.

Offline redhillwoods

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Re: Failure-advice needed
« Reply #26 on: January 23, 2018, 07:51:10 am »
DC, I think you mis-labeled your post. There is no failure here. You're attempting a challenging design that is new to you and your sorting it out. Bravo

Offline joachimM

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Re: Failure-advice needed
« Reply #27 on: January 23, 2018, 09:21:23 am »
Thanks for sharing your experience, even if you consider it a failure, there's a lot to learn from this bow. 

I notice that at full draw, the recurves are still not lifting off the string. Functionally, the bow is 4" shorter than it looks and wheighs. You could cut off 2" from each side, and draw-weight wouldn't change a bit.
This also means you're straining the belly more than you'd expect from the ntn length.

In your next try, I'd also put more reflex mid-limb, and give it shorter or less steep recurves. IMO the ideal is to have lift-off before you're halfway your draw.

Joachim

Offline Marc St Louis

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Re: Failure-advice needed
« Reply #28 on: January 23, 2018, 09:38:12 am »
To elaborate on the deflex in the handle.  I personally find there is no set rule, hence the suggestion to keep it flexible.  I have had a few people ask me how many degrees of deflex does my bow have.  Well I could never answer that question because I don't measure it and I probably have no 2 deflex bows that are alike anyway.  It doesn't seem to make any difference in performance, except for when there's a lot of deflex but that's another story.  I've been able to coax high performance out of straight handle recurves as well as deflexed handle bows.  The thing with the deflex is that you can make a bow a bit shorter for a given draw length, I also happen to like the looks better now.  The highly deflexed bows can be made somewhat shorter but then the bow suffers from other issues that affect performance.

As to the hooks.  I used to like big hooks, for looks and I thought performance.  My thinking change many years ago, even in so far as liking the looks as well.  I now prefer small recurves for looks and they have other benefits.  First of all it is much easier to tiller a bow with small hooks and there may be a slight performance benefit, that one would be hard to prove though.

Pity you can't thin the Bamboo, it is too thick.  Quite frankly I prefer a wood backing for Yew, Maple or Ash
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Offline bjrogg

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Re: Failure-advice needed
« Reply #29 on: January 23, 2018, 10:45:31 am »
To elaborate on the deflex in the handle.  I personally find there is no set rule, hence the suggestion to keep it flexible.  I have had a few people ask me how many degrees of deflex does my bow have.  Well I could never answer that question because I don't measure it and I probably have no 2 deflex bows that are alike anyway.  It doesn't seem to make any difference in performance, except for when there's a lot of deflex but that's another story.  I've been able to coax high performance out of straight handle recurves as well as deflexed handle bows.  The thing with the deflex is that you can make a bow a bit shorter for a given draw length, I also happen to like the looks better now.  The highly deflexed bows can be made somewhat shorter but then the bow suffers from other issues that affect performance.

Thanks Marc, I found that all very enlightening. It all makes sense to me.
Bjrogg
As to the hooks.  I used to like big hooks, for looks and I thought performance.  My thinking change many years ago, even in so far as liking the looks as well.  I now prefer small recurves for looks and they have other benefits.  First of all it is much easier to tiller a bow with small hooks and there may be a slight performance benefit, that one would be hard to prove though.

Pity you can't thin the Bamboo, it is too thick.  Quite frankly I prefer a wood backing for Yew, Maple or Ash
A hot cup of coffee and a beautiful sunrise